Set Array modifier to duplicate the object in both directions
Works with three Modifiers for a x-Axis symmetrical centered model from Front view:


Just add your Array Modifier to your object for the right two duplicates.

Then Add a Cube, translate it 1 BU to the left (minus x-Axis) in Edit Mode (thus keeping its Origin) and scale it up if necessary to encase the complete left half of your Mesh.


Now add a Boolean Modifier behind your Array Modifier selecting this Cube as Object in Difference Mode splitting your center Object in half, optionally hide the cube (H) and afterwards

Add a Mirror Modifier to replicate the right half to the left side...